Worm Composting: How to Make a Wormery

Wonderful, wondrous wiggling worms are the starting point to healthy soil and awesome compost. A healthy compost heap is full of them, but there is another way to turn kitchen scraps and weeds into nutrient-dense goodness: by using a wormery.

Wormeries, or worm composters, use special composting worms to turn kitchen waste into nutrient-dense compost and liquid fertilizer. They don’t smell, take up very little space, and are a great way to introduce children to the wonders of worms. Use one as a standalone composting solution for courtyard or balcony gardens, or as a complement to a traditional compost heap or bin.

How a Wormery Works

A wormery is typically made up of at least two compartments. The bottom compartment collects the liquid, which can be drained off to use as liquid feed for your plants. The top compartment is where the worms live and where you’ll put your kitchen scraps to feed them. This is also where your compost, or worm castings, will be made. A lid keeps everything from drying out or becoming flooded by rain showers.

Two compartments will work, but using a third compartment makes it easier to collect the worm compost.

Holes in the bottom of both the middle and top trays ensure that the liquid produced by the worms can percolate down into the collection tray at the bottom. And once a tray is full, the holes enable worms to migrate up into a new tray, so that compost from the vacated tray can then be harvested.

Making a Wormery

Choose trays or boxes to make your wormery with. We’re using plastic boxes about about 16x20in (40x50cm) and fairly shallow at just 8in (20cm) deep. You’ll also need a simple plastic faucet, a drill and drill bits, and a lid for the top tray.

You’ll also need some worms of course. Don’t be tempted to use worms from the garden – they’re great for tunnelling and improving your soil, but not so quick at composting. You can order composting worms online. We’re using a lively mix of European nightcrawlers and tigerworms capable of eating twice their bodyweight a day!

So let’s assemble the wormery, starting with the bottom tray. Carefully cut out or drill a hole to snugly fit the thread of the faucet. Fit it as low as possible in the tray so that liquid isn’t left at the bottom when you drain it off. Screw it tightly into position then secure with the back nut. You can raise the wormery up on bricks to make it easier to drain off the liquid into a container.

Drill quarter-inch (half-centimetre) holes approximately every two inches (5cm), right across the bottom of both top trays. Drill a single row of holes near the top of the two trays at the same size and spacing. These holes will help to improve airflow, creating a healthier environment for your worms.

Now’s the fun part – time to add your worms! Start with a three-inch (8cm) layer of bedding material. You can use compost or coir fibre, dampened a little to make it nice and comfortable for your worms. They’ll soon bury themselves into that lovely bedding.

Once you’ve added your worms, add a layer of kitchen waste – no more than a couple of inches (5cm) to start with. You can also add a layer of hessian to keep them extra snug. Wait a week before adding any more food, so give the worms time to settle into their new home.

Worms like moist, warm conditions, so keep your wormery somewhere shady and as close to room temperature as you can. They don’t like to be frozen, so move the wormery indoors for winter – into a garage, outbuilding or utility room is ideal.

Looking After Your Composting Worms

Add food a little at a time to the top of the compost. Avoid adding too much food at any one time, as this risks creating an odor that will attract flies.

The worms will digest any vegetable kitchen scraps, including coffee grounds, that you’d normally add to compost, but avoid meat or animal products such as cheese which can attract flies. Go easy on citrus peel and alliums like onion and garlic too, as large amounts will make conditions too acidic for your worms. You can also add small amounts of weeds and leaves, as well as shredded, non-glossy newspaper or torn-up cardboard.

Once the top tray’s full, swap it round with the empty middle tray and start filling that instead. The worms will migrate up through the holes to where the food is, leaving the full tray empty of worms and ready for collection. Repeat this process each time the active tray becomes full up.

Using Worm Compost and Worm Wee

The worm compost, known as worm castings or vermicompost, makes a great all-purpose soil conditioner, or add them to your own potting mixes to give them a nutritional boost.

Drain the liquid off from the bottom tray whenever it collects. This nutritious liquid, often known as worm tea or worm wee, is a super elixir for your plants. Stir one part of the liquid into ten parts water before using.

And there you have it – a superb, home-made wormery that will keep you in wonderful worm castings and lovely liquid fertilizer. If you already have a wormery, tell us about it! What do you do with all that goodness and how have your worms benefited your gardening? Let us know down below.